Interesting thread. I’m not sure if this link has been posted, but I think CA provides a more than adequate argument for the existence of purgatory. (One of many on this site.)
catholic.com/thisrock/2000/0010sbs.asp
Here’s a quote taken from the link:
I find the Protestant attack on the concept of purgatory to be facile at best with a strong dependence on the theological construct of sola scriptura (or should I say “verses scriptura”) which is even less supported by “scripture” than the idea of purgatory. In essence, we have strong evidence of prayers for the dead throughout the Bible (with or without the deuterocanonicals) as well as the strong concept of purgatory taught by the early Church fathers. We have multiple early Christian writings which speak clearly of prayers for the dead as a beneficial effort to help their continuing sanctification.
Therefore, I think Protestants have a hard time cut out for themselves. Not only do they need to prove that prayers for the dead didn’t exist as an early Church teaching (they did…), and that the Bible doesn’t mention implicitly or allude to this same concept (it does…), but they need to explain how exactly the Church got it wrong for so long. If people were praying for the benefit of the dead, how exactly were the dead benefiting? They certainly couldn’t benefit from Hell, and how could they benefit any more while in Heaven? Therefore, where exactly were these souls that were being prayed upon?
Here’s the best part though as far as I’m concerned. Martin Luther initially claimed in 1519 during the early Protestant Reformation that the existence of Purgatory was undeniable, yet by 1530 he had decided that it was, in fact, deniable. It took him 11 years to come to this conclusion.
I sometimes wonder what convinced Luther that 1500 years of Catholic Church teaching and tradition passed down from the earliest of Church fathers was so misguided and not the work of the Holy Spirit. What exactly gave him, and him alone the perspicaciousness to pick and choose which components of the Faith were inspired of God and which were not? Divine inspiration or arrogant presumption?

And today we can see the fruits of his work, a divisive and heterogeneous Church with each denomination bickering among themselves and claiming to be privy to the “divine interpretation” of Truth.
In either case, I’ll leave the Protestants with this olive branch… If Luther, the progenitor of your “reformed theology”, could “flip-flop” on an issue such as Purgatory over an 11 year period of reflection, then the least you can do is give Catholics the benefit of a doubt where the teaching is concerned. After all, Luther’s behavior could be construed as constituting a tad bit of, shall we say, uncertainty on the issue.
God bless.